(First Background Art)
In a network system in which a plurality of devices are connected, in order to identify devices which become communication targets, a control address such as an IP address is written or a hardware address uniquely allocated to an apparatus such as a MAC address is used. For this reason, in a case where a device is replaced or an arrangement change of the device is performed, each time, it is necessary to conduct an initial setting by assigning an IP address to a new device or registering an MAC address allocated to a new device.
However, the initial setting of this type is difficult for an ordinary user to conduct and it is necessary to ask a service company, which leads to a high maintenance cost. In view of the above, as one of solutions for such a problem, an IP address setting method of automatically allocating an IP address to each device connected to a network by using a DHCP is known. Still, even if this DHCP is used, in a case where an IP address is set in accordance with an installation location, it is necessary to associate the IP address with the MAC address in advance. Thus, each time the device is replaced or the arrangement change is performed, this association operation needs to be carried out.
Also, as a method of facilitating the IP address setting, Japanese Unexamined Patent Application Publication No. 2005-176279 discloses a network system in which each device connected to a network automatically transmits an IP address to a management apparatus for managing IP addresses when a power supply is turned ON, and thus a setting operation of IP addresses for the management apparatus becomes unnecessary.
(Second Background Art)
Up to now, in order to prevent an overload of a power supply socket or an electronic circuit, a large number of countermeasures are proposed such as “apparatus for performing overload protection for circuit” described in PCT Japanese Translation Patent Publication 2004-515034.
(Third Background Art)
Up to now, in order to prevent a tapping or an unauthorized access in a network system including a LAN or the like, a large number of countermeasures are proposed such as “method for secret protection in network data transfer” disclosed in Japanese Unexamined Patent Application Publication No. 2005-26825.
In addition, as a countermeasure commonly used, a security function referred to as “MAC address filtering” is famous. According to this MAC address filtering, a MAC address of a device (a device connected to a network) which is permitted to perform a communication (an inherent hardware address of the apparatus) is registered in advance in a router or an access point (a network relay apparatus). Only in a case where the registered MAC address is matched with a transmission source MAC address of the device which requests the communication, an access is permitted. Then, a communication of a device other than the registered device (a communication from outside of the network) is rejected.
(Fourth Background Art)
In a case where a plurality of printers are connected on a network and a use/management is carried out, in order to distinguish the respective printers, a network address is assigned to each printer and the use/management is carried out on the basis of the network address.
An example of a use management method for the printers includes a method of using two types of network addresses, which are a MAC address assigned to a NIC (network interface card) of a printer and an IP address of a printer directly assigned by a user. In a case where a communication is conducted between two information instruments (for example, between a printer and a management server), a transmission source information instrument performs a communication by transmitting a packet in which at least a transmission source IP address and a MAC address of an adjacent information instrument (for example, a router) are added to data.
In addition, an example of a method of assigning an IP address to an information instrument includes a method of directly assigning the IP address, but such a method is known that a server broadcasts a setting protocol including a MAC address of a printer on a network, and when a MAC address which a printer has is matched with the MAC address of the setting protocol, an IP address of the setting protocol is obtained (for example, Japanese Unexamined Patent Application Publication No. 11-249989).